1. Field of the Invention
The present invention relates to a distributed network node, and particularly to a distributed network node in which children stations are remotely arranged and to a distributed network management method.
2. Description of the Related Art
One of the anticipated characteristics of a communication connection device is the remote installation of extended nodes (children stations). This characteristic is desirable because the interfaces in a communication connection device that provide various services may be distributed, rather than being concentrated in one fixed location. Communication connection devices are usually installed in locations that are convenient to users, and more compact and inexpensive devices are therefore always being sought, and the development of each individual interface must be simplified. At the same time, the varieties of interfaces cover a wide spectrum, and it is therefore necessary to aim for a design that can optimize the physical size, power consumption, and thermal characteristics necessary for each individual interface, to allow for flexible alteration or expansion of functions, and to accommodate alteration of specifications according to use. A distributed network nodes that enables independent development of each individual function is therefore in demand.
Japanese Patent Laid-open No. 98524/98 is one example of such a distributed network. In the distributed network in this invention, an exchange node that integrates a control system device and speech system device in the prior art is separated into a control system node, which includes a control system, and a speech channel system node, which includes the speech channel system; a plurality of speech channel system nodes being controlled by a plurality of control system nodes.
However, a problem in the prior-art distributed network node as explained hereinabove was the difficulty of optimizing or reducing the size and cost of the case that constitutes each node. In the prior-art distributed network, each control system node and speech channel system node that make up each individual node was provided in a single case. As a result, all of the functions necessary as a node had to be incorporated into each individual case for each individual control system node or speech channel system node, and this necessity made it difficult to provide a case that optimizes the necessary functions, or to make the case smaller or less expensive.
In particular, an approach has become necessary that can handle, on the network-side, the types of terminal-side entities such as a LAN that are now increasing in variety.
When it comes to applying these interface variations to the network, the variations must be considered one by one in the network, and building a wide range of interfaces into a single case placed a considerable load on each node. As a result, there was difficulty in reducing size, lowering costs, and optimizing, and a suitable remote arrangement of nodes was not possible.
The present invention was developed in view of these problems, and has as an object the provision of a distributed network nodes in which nodes are smaller and less expensive, and moreover, easy to optimize, and that allow independent development of necessary interface functions.
To achieve the above-described objects, the invention described in the first claim of the present invention is a distributed network node of a network, in which main signals are sent to and from the distributed network node. The distributed network node comprises a core node and a plurality of extended nodes. The core node comprises: an Operation Administration and Maintenance (OAM) function part for generating OAM signals used to manage the extended nodes, and a common function part for carrying out the processes of transmitting and receiving main signals to and from both the network and the extended nodes and transmitting and receiving the OAM signals to and from the extended nodes. Each extended node comprises: an interface function part for carrying out interface processing for that extended node; and a common function part for processing main signals received from the core node.
According to the distributed network node of the first invention of the present application having the above-described configuration, the core node, which is the parent station, is provided with OAM functions for managing extended nodes and common transmitting/receiving functions with the extended nodes. In addition, the extended nodes, which are child nodes, need not be physically incorporated in the core node, and may have independent individual interface function parts. Furthermore, since the extended nodes are controlled by the core node, there is no need to provide OAM function parts in the extended nodes, and the optimum interface functions for each individual environment can be provided. Extended nodes can therefore be made smaller, less expensive, and the extended node case can be independently developed, thereby allowing a design that optimizes physical size, power consumption, and heat characteristics.
In the invention described in claim 2 of the present invention, the extended nodes and core node described in the first claim are each arranged at prescribed locations and housed in independent cases, and connected by transmission lines for exchanging the main signals and the OAM signals.
According to the distributed network node of the second invention of the present application having the above-described configuration, the extended nodes need not be physically incorporated in the core node, and extended nodes can be connected to the core node by main signals and control signals and installed remote from the core node. In addition, optimum extended nodes that are adapted to their environment can be arranged because their cases can be designed according to the installation locations.
The invention described in the third claim of the present invention is a distributed network node in which the common function parts of the extended nodes described in the first and second claims each further include: receiving means for receiving the same signal transmitted over two differing routes; comparing means for comparing both signals that are received by the receiving means; and selecting means for selecting one of the signals according to the result of the comparing means.
According to the distributed network node of the third invention of the present application having the above-described configuration, when transmitting the same signal over two differing routes from the transmission section of a node, the signal can be reliably received despite the occurrence of a fault on either of the paths by selecting on the receiver side the signal that has not been affected by the fault.
The invention described in claim 4 of the present invention is a distributed network node in which the common function part and interface function part of each of the extended nodes described in claims 1, 2, and 3 are connected only by signal lines for exchanging the main signals and the OAM signals.
According to the distributed network node of the invention of the fourth invention of the present application having the above-described configuration, the connection section of an extended node is constituted by a circuit that is common to the core node, and interface function parts can be individually selected, whereby the mode of connection with each signal (main signals and OAM signals) can be easily developed to match the environment.
In addition, the invention described in claim 5 of the present invention is a distributed network node in which the extended nodes and the core node in the inventions described in claims 1, 2, 3, and 4 are connected in a star configuration.
According to the distributed network node of the fifth invention of the present application having the above-described configuration, a plurality of extended nodes that provide various services from the core node can be connected by optical fiber or metallic or radio lines, and can be installed in locations separated from the core node. In addition, since the functions of the installed extended nodes can be constructed independently as appropriate to their environment, a design is possible that optimizes the physical size, power consumption, and thermal characteristics.
The invention described in claim 6 of the present invention is a distributed network node in which the extended nodes and core node in the invention described in claims 1,2,3, and 4 are connected in a ring configuration.
According to the distributed network node of the sixth invention of the present application having the above-described configuration, a more compact and less expensive core node is possible because only two extended node interfaces are required in the core node. In addition, if more extended nodes are provided, one end of the ring connection may be cut and the extended nodes then added. Additional nodes can be established without affecting the extended nodes even if faults in signals should occur due to cutting at this time, because one end of the connection remains in connection.
The invention described in claim 7 of the present invention is a distributed network node in which the extended nodes and core node in the invention described in claims 1, 2, 3, and 4 are connected in a double-ring configuration.
According to the distributed network node of the seventh invention of the present application having the above-described configuration, the distributed network nodes can be configured in a main ring and sub-ring by connecting nodes in a double-ring configuration; wherein the long-distance portion can be constituted by the main ring, and a campus, a mall, or small offices and home offices can be constituted by sub-rings from each extended node of the main ring, thereby achieving a node configuration that is balanced in terms of distance.
In addition, the invention described in claim 8 of the present invention is a distributed network node wherein the core node of claims 1, 2, 3, 4, 5, 6, and 7 is in duplex form.
According to the distributed network node of the eighth invention of the present application having the above-described configuration, a highly reliable core node can be provided by constituting the core node in duplex form, whereby the occurrence of a fault in one of the core nodes does not affect services that are provided to all nodes that are connected to the core node.
The invention described in claim 9 of the present invention is a distributed network node in which the extended nodes of the invention described in claims 1, 2, 3, 4, 6, 7, and 8 include a clock processing means that, when signals received from one side are outputted to the other side, outputs to the other side using a clock that is extracted from the received signals.
According to the distributed network node of the ninth invention of the present application having the above-described configuration, the extended nodes can be configured to use an extracted clock without including a clock source (oscillator) because the extended nodes are configured subordinate to the core node. In this case, signals are transmitted from the transmitting side by two different routes, and signals of one route can be received even if a fault should occur on the other route, thereby enabling highly reliable signal transfer in which the entire network is unaffected even without a clock source.